경량화용 CFRP/Foam 부재의 에너지흡수 특성

Abstract

The most important goals in designing automobile are safety and environment-friendless. Vehicle structure must be lightweight in order to improve fuel-efficiency and reducing exhaust fumes. Therefore, the designing vehicles should be more concerned on the aspect of securing safety performance, the while, it also should consider reducing weight of vehicle structural member. CFRP(Carbon Fiber Reinforced Plastics) of the advanced composite materials as structure materials for vehicles, has a widely application in lightweight structural materials of air planes, ships and automobiles because of high strength and stiffness. In the study, one type of circular shaped composite tube was used, combined with polyurethane foam. Experimental investigations are carried out for CFRP circular members in order to study the effect of various stacking condition. Static collapse tests were performed with change of the stacking condition, such as fiber orientation angle, interface number and density of polyurethane foam. Collapse mode and energy absorption characteristics were analyzed. Following the above study, conclusions are drawn as below;

1. Test specimen showed the crushing on triggered direction, and external layer was affected significantly. In addition, energy absorption performance was improved when the direction of first was 90° and thickness of ply in 90° was high. 2. The CFRP side member was collapsed according to the different orientation angles by compounding of the 4 different modes: transverse shearing, laminar bending, brittle fracture, and local buckling. When the fiber orientation angle is small, the member absorbed energy by laminar bending. As the fiber orientation angle increases, the member was absorbed energy by local buckling and matrix crack due to transverse shearing. 3. For 0° of external layer, absorption energy was increased with number of interface number, but 90° displayed the reduction in absorption energy and increase in afterward. 4. By filling of empty space in CFRP circular member with polyurethane foam, total absorption energy and means load was increased for 30~40% and 20~50%, respectively.